I want to preface by saying that I am aware this is a contentious issue, I do not want to raise negative emotion by bringing this up, merely to try to shed light on outstanding issues with Classic WoW.
Many batching interactions that occur now certainly occurred in Vanilla. NPC’s hitting you after a stun, tanks dying after getting a heal, Rogues being hit out of Vanish, these are all gameplay interactions that definitely happened with original batching.
But, there are many interactions that behave differently in Classic, because the code has not been recreated properly. The most egregious example I can think of is issues with pets and feign death. Delays to pet commands are excessive in Classic; pet responsiveness was certainly higher in Vanilla. With feign death, a delay to dropping combat is also excessive, and again, was not noticeable in Vanilla (though feign death certainly bugged out sometimes!). There are countless other examples of bizarre batching interactions that did not used to exist but I want to keep it brief.
The issue is that in original Vanilla, certain commands/actions, spells, and effects were put on a high priority batch. These were intended to be processed quickly, so that certain fundamental gameplay interactions did not feel sluggish.
In Classic, it appears as though much of this code has been inaccurately emulated. This is a result of the batching being BFA batches scaled up, rather than using the original code. Blizzard attempted to fill in the rest of the code for how batching worked… but got many things wrong.
The result of this is what many players report as something feeling “not right” about how Classic WoW plays compared to memory. It is many small interactions being put on a long batch, that were never intended to be long batched in the first place.
I hope for some positive changes with batching, but my hopes are not high, as we’ve had over a year of Classic and many of the issues with batching simply have not been addressed…